This invention generally relates to a holder for electrical fuses and more particularly to a fuseholder which may be panel mounted with electrical connections thereto being made behind the panel.
Examples of such a panel mounted fuseholders are shown in U.S. Pat. Nos. 3,828,291 and 3,177,318, which are assigned to the same assignee as the present invention. Typically, such a panel mounted fuseholders include a base and a detachable head adapted for joinder. The most common fuses for use with these fuseholders are miniature, cylindrical, glass type fuses having conductive end caps or ferrules. One end of such fuse is ordinarily inserted a fraction of its length into a conductive cylindrical chamber within the head of the fuseholder and is generally held there by a leaf spring or friction fit. The fuse and head assembly is then inserted into the base where the second or bottom end cap or ferrule of the fuse makes electrical contact with a rear terminal of the base of the fuseholder.
Normally, an extended portion of the conductive chamber of the head of the fuseholder protrudes into the base where it makes electrical contact by a bayonet or friction connection with a side terminal piece. The head, commonly, includes a helical compression spring within the conductive cylindrical chamber to press the fuse into good electrical contact with the rear terminal and to bias the head away from the base to ensure a good electrical connection at the bayonet between the conductive head chamber and the side terminal. However, conventional bayonet connections will only make reliable electrical contact when the bias between the head and base is sufficiently maintained. Any outside pressure on the head or jarring or vibration of the fuseholder is likely to cause the connections to open. This opening may be produced by accidental or deliberate pushing of the head or may occur because of vibration or the like produced in the environment in which the fuseholder is used, such as, for example, in moving vehicles or in areas where physical contact or natural occurrences cause instability. Opening of these contacts causes a power loss to circuit units protected by the fuse. This could in turn cause holding contacts to drop out, units to shut down, loss of vulnerable memory, long restart or warm-up times, and even unit damage due to voltage and current transients.